Weed started to work in the motion picture industry in the early 1980s while employeed at Chris Walas, Inc. As creature crewmember and model maker he contributed to feature films such as the action adventure Romancing the Stone (1984), the horror comedy Gremlins (1984), the television fantasy film The Ewok Adventure (1984), the science fiction drama Enemy Mine (1985), the short science fiction film Captain EO (1986), the horror film The Blob (1988), the horror sequel The Fly II (1989), the science fiction sequel RoboCop 2 (1990, starring Peter Weller), the horror film Arachnophobia (1990), and the comedy sequel Look Who's Talking Too (1990, starring Kirstie Alley).

In a 2010 interview, Weed recalled how he started out professionally, "My first professional gig was indeed on the first Gremlins movie back in 1983. I had been working on a low budget horror movie in San Francisco called Dracula's Disciple, and through the connections I made there mixing gallons of fake blood, I was hired at creature effects studio Chris Walas (CWI). When I joined Gremlins I was 19 and still in college, so I decided to take a semester off and see how things went. I came on the Gremlins project just as there was a big push to build the dozens of background puppets for the movie theater scene. I had a great time learning how to make proper molds and cast foam rubber Gremlin body parts. While Mr. Spielberg himself didn't actually hire me, it sure was a stroke of luck to be on that project, learn the trade, and then have the resulting film become such a landmark in the creature effects industry."

Further film work includes the comic adaptation Batman Returns (1992), the horror film Dracula (1992), the fantasy comedy Hocus Pocus (1993), the comic adaptation The Flintstones (1994), the thriller Clear And Present Danger (1994), and the action thriller Mission: Impossible (1996).

In 1987 Weed permanently joined ILM (though for awhile continuing to work for Chris Walas on an ad-hoc basis), and has remained in their service ever since. Weed further recollected in the 2010 interview, "I had just returned from working in Toronto on The Fly[1986] for CWI. The shop had some down time so I gathered my meager portfolio and cold-called the ILM Model Shop for an interview. As it turned out, the timing was perfect. They had just completed Howard the Duck and were about to mount a major organic effects film called Inner Space. I was interviewed by ILM model shop supervisors Charlie Baily and Jeff Mann for the job of building half scale puppets of Kevin McCarthy and Fiona Lewis. That interview went pretty well and I started the next week. Really, I couldn't believe my good timing." [1] In the same year, immediately after Innerspace, Weed became part of the team that built the studio model of the Enterprise-D.

For ILM, Weed worked as technician and model maker on the fantasy film The Witches of Eastwick (1987), the fantasy sequel Ghostbusters II (1989), the drama Fire in the Sky (1993), the adventure Congo (1995), the sequel The Lost World: Jurassic Park (1997), and the science fiction comedy Men in Black (1997). More recent credits for ILM included the special edition of the science fiction sequel Star Wars: Episode V - The Empire Strikes Back (1997, in which he played the Wampa creature, albeit uncredited).

Around 1999, Weed made the switch to digital modeling and has predominantly worked as digital modeler and digital artist on further productions like, the prequel Star Wars: Episode I - The Phantom Menace (1999), the science fiction drama Artificial Intelligence: AI (2001), the science fiction film Minority Report (2002), and the sequel Terminator 3: Rise of the Machines (2003, starring Kristanna Loken), Star Wars: Episode III - Revenge of the Sith (2005), the remake War of the Worlds (2005), the first three Pirates of the Caribbean films (2003, 2006, and 2007), the science fiction film Transformers (2007), the adventure Indiana Jones and the Kingdom of the Crystal Skull (2008), the science fiction thriller I Am Number Four (2011), J.J. Abrams' Super 8 (2011), the science fiction films Cowboys & Aliens (2011) and Battleship (2012).